The present invention relates to a method for producing breathable leather material as well as the use of a leather material produced according to the method.
Leather materials, which are to say natural leather and also synthetic leather, are used widely in the textile industry, but also in the field of motor vehicle equipment. Until a leather material can be provided for further processing, it is subjected to a complex production process. For example, natural leather, which is to say raw leather, is tanned, stretched, walked and finally provided with a finishing that makes the leather more durable and, most of all, resistant to stains and permanently water-repellent. The finishing can include one or more layers, including pigment-carrying layers. To ensure that the quality of the leather material remains continuously good, it has to be breathable so that, for example, moisture does not adhere to the leather material and lead to mould stains there. To that end, in a final step, the leather material is mechanically perforated after the finishing has been applied. In this process, it is a disadvantage that the perforation, which is added later, leads to a strong adverse optical effect on the surface of the leather material and, therefore, mars the appearance of said surface.
Proceeding from this prior art, it is therefore the object of the present invention to provide a method for producing a breathable leather material, which is easily realizable and avoids any adverse optical effects on the appearance of the leather material. Furthermore, it is an object of the invention to provide a use for leather material produced according to the method.
These and other objects of the invention are achieved by a method for producing breathable leather material according to the invention, with the acts of: i) providing a leather-based material; ii) perforating the leather-based material; iii) providing a support body; iv) applying a finishing to the support body so that a later visible side of the finishing faces the support body; and v) transferring the finishing to a surface of the leather-based material and removing the support body.
According to the invention, the term “leather material” encompasses any natural leather product as well as synthetic leather or leather-like textile material. Perforating only the leather-based material before applying the finishing achieves the following effects: for one, it makes the leather-based material breathable. Because the finishing is applied to the perforated surface of the leather-based material in a further step, the perforations are furthermore optically masked. So as not to reduce the breathability of the leather material, a special application method is used to apply the finishing to the leather-based material, that is to say, a transfer of a finishing applied in advance to a support body. If the finishing were applied directly to the leather material, which in this case is already perforated, by spraying, rolling or by dipping the leather-based material into a finishing preparation, the finishing would clog the perforations because of the viscosity of the finishing preparation. This is prevented with the method according to the invention. The finishing is performed by the local, punctiform or planar application to the support body, for example, of a film material, and loses its flowability to the extent that it does not flow off the support body, but nevertheless has good adhesion properties on the leather-based material. However, any flow into the perforation is prevented. Therefore, a mechanical after-treatment to develop the breathable properties is not necessary. The method can be realized in a simple fashion without any high technical effort by combining standard processes. Furthermore, a precise punctiform application of the finishing on the leather-based material can be performed, which promotes an economical use of the finishing in terms of material and lowers the costs of the method according to the invention.
An advantageous modification of the method according to the invention is characterized in that the finishing is applied punctiformly to the support body. This not only increases the efficiency of the material but also improves the breathability of the leather material. Because of the punctiform application of the finishing to the support body, the application pattern is retained even after the finishing is transferred to the surface of the leather-based material. Thus, the finishing itself is effectively “perforated.” The application of a “perforated” finishing cannot be realized in a satisfactory fashion with the previous methods. An application of the finishing by means of a screen-printing process has turned out to be especially advantageous in terms of a simple, technical implementability.
An additional improvement of the breathability of the leather material can be achieved in that the support body is perforated before the finishing is applied.
For the same reason, the support body and the finishing can also be perforated before the finishing is transferred to the surface of the leather-based material.
Because of the statistical distribution of the perforation holes in the leather-based material and also in the finishing and/or in the support material and the finishing, whether through punctiform application of the finishing or through perforation of the support body and/or the finishing, a large part of the perforations in the leather-based material is covered so that there is a low adverse optical effect, but a leather-based material with good breathable properties can be provided.
Transferring the finishing to the desired surface areas of the leather-based material can occur in any way that generates sufficient adhesion of the finishing on the leather-based material and facilitates a largely residue-free removal of the support body. Under these aspects, it is preferred that the support body and/or the finishing are heated to transfer the finishing. Heating the support body and/or the finishing reduces the adhesion of the finishing to the support body and facilitates a bonding to the leather-based material. Preferably, a non-stick coated support body, for example a silicon-modified film, which additionally facilitates a removal of the finishing from the support body, is used as the support body. Other auxiliary devices, such as a scraping off device, for example, are also advantageously possible.
The adhesion of the finishing at the surface of the leather-based material can be improved by pressing the exposed side of the finishing to the surface of the leather-based material to transfer the finishing. This can be done, for example, by means of a stamp or a roller.
The finishing that is used is not limited per se and is selected depending on the desired surface property of the leather material. In particular, the finishing comprises a primer and a coloring preparation, such as, for example, a pigment dispersion and/or a topcoat. In particular, the topcoat thus seals the surface and makes it scratchproof and dirt- and water-repellent. The preparation can be applied in one or in multiple coats, at the same time or successively, using the method according to the invention.
To produce an especially high-quality natural leather product, the leather-based material is a natural leather, and is first tanned, stretched and/or walked before it is provided.
Also according to the invention, the use of a leather material produced according to the method described above is described, which in particular comprises the production of a molded skin and/or a motor vehicle trim element, in particular an instrument panel, a center console, a door trim, or a seat cover, with breathable properties.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.